The present invention relates to equipment for sensing the presence or absence of objects, and more particularly to detecting whether an occupant is present in a seat of a motor vehicle.
As a safety feature, modern motor vehicles incorporate air bags into the steering wheel in front of the driver and into the dashboard in front of a passenger in the forward seat. Additional air bags are being proposed for the doors to the sides of these occupants. Rapid deceleration of the motor vehicle during an accident is detected and activates inflation of the air bags which the cushion the occupants.
Although air bags have greatly decreased the severity of injuries from motor vehicle collisions, they occasionally cause injury to the passenger or driver because of the rapid rate with which the air bag must be deployed. In particular, the air bag may severely injure a small child or infant sitting in the front seat of the vehicle.
As a consequence, it is now recommended that small children and infants ride in the rear seat of the vehicle so as not to be exposed to the force of air bag deployment in the event of an accident. However, that does not address the situation which occurs when that recommendation is ignored and a child rides in the front seat of the vehicle. Furthermore, in two passenger vehicles, such as sports cars and trucks, a child or infant must be placed in a seat that faces an air bag. In this latter situation, it has been proposed to provide a manual override switch which will disable the air bag in front of the child. However, not only must this switch be manually operated whenever a child is present, the motor vehicle operator must remember to re-activate the air bag for adult passengers.
These precautions also do not address the presence of a relatively small adult occupant in a vehicle with an air bag designed to protect an larger person. Thus there is a need to be able to customize air bag operation in response to the size of an individual in the seat that is protected.
However, in order to dynamically configure the air bag, its control system must be able to reliably determine the occupant""s size. One approach that has been suggested is to sense the weight of the person sitting on the seat. However, weight alone does not indicate the kinematics of a person during a crash. For example, a person with a low center of gravity and small upper torso will have dramatically different kinematics as compared to a person with a small waist and muscular upper body. That distinction in crash kinematics is very important in dynamically configuring air bag operation.
A general object of the present invention is to provide a mechanism for detecting the presence or absence of an occupant in a seat within a motor vehicle.
Another object is to implement that mechanism by means of a stereoscopic image processing system.
A further object is to provide such a system with the capability of determining the size of the seat occupant.
Yet another object of the present invention is to provide such a system with the capability of determining the sitting position of an occupant.
Another aspect of the present invention is to provide the stereoscopic image processing system with the ability to detect motion in order to distinguish inanimate objects placed on the seat.
A further aspect of the present invention is to provide information for configuring the operation of an air bag in a motor vehicle to conform to the physical characteristics of the seat occupant.
An additional aspect is to provide information about the occupant""s kinematics in real time during a crash which would enable dynamic optimization of air bag performance.
These and other objects are satisfied by a stereoscopic object detection system which includes a pair of cameras that produce first and second images of the seat. Elements in the images are shifted in position between the first and second images by an amount corresponding to a distance the elements are from the cameras. A distance processor calculates the distances that a plurality of features in the first and second images are from the pair of cameras based on the shift of the position of those feature between the first and second images. An image analyzer determines presence of an object on the seat from the distances. The image analyzer also may determine the size of the object from the distances
In the preferred embodiment of the stereoscopic object detection system, the distances are employed to detect movement of the object on the seat and the rate of that movement. Pattern recognition also can be performed on the distance information or on one of the first and second images to categorize the object.
In one application of the present invention, the image analysis results are used by a mechanism to control operation of a device on the motor vehicle. For example those results may be employed to configure deployment of an air bag in the motor vehicle to correspond to the physical characteristics of a person on the seat.